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There are multiple switches and buttons in the cockpit, with different shapes and layouts. Are they spill proof?

What if the pilot spills water or coffee on them, will they still function?

Notts90
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Firee
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    You know, I've flown for over two thousand hours and never thought of this. Good question! – Steve V. Mar 26 '15 at 12:28
  • Thanks, because at first I was thought it might be too stupid to ask such a question. – Firee Mar 26 '15 at 15:05
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    See the 1960's movie, "Fate is the Hunter"... – DJohnM Mar 26 '15 at 17:17
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    No, they are definitely not. Aircraft technology has sort of a stone age feel to it. Its not like a Sony media deck or something. In some aircraft like crop dusters and stuff there are even no panels, so there are tubes and wires running everywhere along the walls. You are thinking, boy I hope I don't bump into that gas line. Its like a Kafka novel. – Tyler Durden Mar 26 '15 at 17:35
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    Perhaps it would be cheaper to have the pilots drink from sippy cups instead. – Aron Mar 27 '15 at 09:35
  • My instruments are all mounted in vertical panels in front of me, there is no unintentional way to splash stuff forward on to any instruments, gages, displays, switches, etc. Only the fuel selector on the floor is subject to any wetness, and it's a sealed unit, so a spill would not bother it. I've owned the plane since 1996 and nothing has even been spilled. Drinks have been from bottles with screw-on lids, and we don't tend to have more than a snack during a 3 to 3.5 hr flight. – CrossRoads May 16 '19 at 12:52
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    No, and that's why you never make jokes in the cockpit. *8P – Juan Jimenez May 16 '19 at 12:57

2 Answers2

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No they are not, at least not fully. There have been instances of equipment failure caused by coffee spills, resulting in the need to abort the flight.

This example shows a flight that needed to divert because a coffee spill disabled the communication equipment.

This Boeing 707 had to make an emergency landing after the crew inadvertently spilled water on the autopilot panel causing the stabilizer trim wheel started to rotate. Control was lost as the plane pitched up and down. Three people died in the accident.

This Boeing 737 report had smoke in the cockpit because the previous flight crew spilled coffee and sugar over the avionics.

This Boeing 720 suffered control problems (resulting in Dutch roll) after a coffee spill cause a short circuit in the yaw damper.

This Airbus A330 diverted for an emergency landing after liquid was spilled onto electronic devices in the cockpit causing the smoke.

Burned electrics

Source: Transport Accident Investigation Commission of New Zealand

DeltaLima
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    Good explanation. Does this mean there are regulations by FAA, on what type of food /drinks a pilot can consume in the cockpit, or is it a known issue, which we all have to live with? – Firee Mar 26 '15 at 15:07
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    As far as I know there are no limitations to what type of food/drinks a pilot can consume in the cockpit based on this hazard. It's a relatively rare occurrence. There are some recommendations on designing and testing for protection against spills of beverages, but nothing strict. – DeltaLima Mar 26 '15 at 15:24
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    I find this weird. The equipment is tested for so many things, and even making it moderately spill proof doesn't add that much to the already enourmous costs. And given that pilots regularly eat and drink, it makes me wonder if there is not maybe another reason why it is not done. – PlasmaHH Mar 26 '15 at 15:28
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    @PlasmaHH I'm more surprised that pilots simply don't use spill-proof cups. C'mon, you give several hundred cups to the people on board and you can't afford couple cups with good lids for the crew? ... – yo' Mar 26 '15 at 16:15
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    @yo': are those still spillproof when they slam at the windshield turing turbulences? What about spraying it all over the avionics because you couldn't hold it anymore since the chief steward told such a dirty joke? And I doubt they have invented spill proof tables for the food yet... ^^ – PlasmaHH Mar 26 '15 at 16:19
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    @PlasmaHH Food is less a problem. I've got pasta with sauce on my notebook and I didn't worry, just fliped it upside-down instantly and cleaned it with napkins, but coffee has already almost destroyed it. And for spill-proof cups, think baby-bottle, but with not a babyish shape and with a straw instead of a nipple. Actually, if you cut a larger hole in the nipple and put a straw through it, the result is very convenient and very spill-proof (says a scoutmaster that saw it used in some "violent" scout game). – yo' Mar 26 '15 at 16:22
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    @yo': I have seen quite liquid sauces being served in airplanes, and passengers rarely like it if the avionics is turned upside down to clean it with a napkin. That said, notebooks are made for toleraing a little more dirt, the ways from they keyboard into the electronics is often hard if not impossible to penetrate by pasta sauce. But imainge an avionics panel with the sauce already in the relatively big slits, impossible to clean, and slowly dripping down, causing high impedance shorts that turn into low impedance carbon and sparks three weeks later... – PlasmaHH Mar 26 '15 at 16:26
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    @yo' So if the pilot spills pasta on the controls should he just turn the plane upside down and give a good shake? – CaptainCodeman Mar 26 '15 at 16:26
  • @PlasmaHH I was implying that a sauce is slow to propagate anywhere, leaving you time to remove it. I should have made myself more clear. – yo' Mar 26 '15 at 16:30
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    @yo': my point is that you don't have the time. It already made its way into the innermost parts of your device. You were lucky with yours, but the pathway into vital electronics is much less obstructed than for your notebook. Also a lot of sauces have a much lower viscosity than average pasta sauce. There is always a decent chance that as soon as it hit the avionics, something went into it. – PlasmaHH Mar 26 '15 at 16:35
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    Ironically, probably the only thing that electronic equipment doesn't mind being spilled on it is liquor. – Danny Beckett Mar 26 '15 at 18:45
  • @DeltaLima : Does a rare occurrence event not given much importance in the aviation industry, or do they need something catastrophic to happen for their attention ? – Firee Mar 27 '15 at 11:09
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    @Firee Things are balanced based on risk assessments. A rare occurrence can be very important if the potential outcome is very likely to be catastrophic. But you don't necessarily need a rule or regulation to improve safety. Avionics panels build today have much better ingress protection that those from the '80s, I imagine that most manufacturers nowadays will throw coffee over their products as part of testing. – DeltaLima Mar 27 '15 at 11:51
  • @CaptainCodeman yup, flip it upside down and find some turbulence, you'll be right as rain. – Jae Carr May 23 '15 at 15:07
  • The 737s really had a bad day... – dalearn Jan 11 '18 at 18:34
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    On a side note. It always appears when flying coach that turbulence always increases just as they serve the coffee. I always figured it was because the pilot is flying with one hand.... or his knee.. when they used to allow smoking on board.. J/K – Trevor_G Jan 11 '18 at 21:31
  • That third one was a 720B (a development of the 707), not a 737. – Vikki Apr 17 '18 at 18:44
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On the old Zeppelins all electrical switches were enclosed, with the actual switching contacts submerged in oil to avoid sparks. And Zeppelins had a lot of switches, containing much more electrical equipment than typical aircraft of their times. All these switches were also spill-proof by design. Airship engineering seems to be a lost art ...

Left: Radio operator of a WW I Zeppelin at his equipment, right: Elektroraum of the LZ 127

Left: Radio operator of a WW I Zeppelin at his equipment, right: Elektroraum of the LZ 127.

Peter Kämpf
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    Zeppelins were also notoriously flammable. I don't think there have been enough cases to justify fully insulating electronics against liquids. – Ambo100 Mar 26 '15 at 17:03
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    In college, I worked at a large power transformer factory and they used oil as electrical insulation. The fact that oil is an electrical insulator is still mystifying to me. Probably a better question for chemistry.SE or electronics.SE... – FreeMan Mar 26 '15 at 17:21
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    Zeppelins LOL +1 – Tyler Durden Mar 26 '15 at 17:33
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    I'd guess that the decision to do this had something to do with the giant volume of Hydrogen gas, which had a nasty habit of quickly becoming water plus heat in the presence of sparks. – reirab Mar 26 '15 at 18:00
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    You can imagine that battleships had much better spark protection in their powder magazine than on the bridge, for a similar reason. – Gabe Mar 26 '15 at 18:36
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    @FreeMan It depends on the oil. Transformers don't use oil only because of insulating purposes (although this is the case as well), but they use it for coolant as well, considering that mineral oil is typically a better conductor of heat as compared to air. If a transformer loses its oil, it'll overheat, or arc internally, and melt. – Sargun Dhillon Sep 30 '15 at 23:28